There are known water supply control systems for use with toilets or the like, wherein an optical means detects whether there is a user or not, and water is appropriately supplied through a faucet.
In such a water supply control system, the optical means detects a human being by energizing a light-emitting element, for example, to apply light to the human being, and detecting reflected light with a light-detecting element. If the water supply control system is powered by a battery, the light-emitting and -detecting elements are generally energized periodically (intermittently) in order to prevent quick consumption of the battery.
When the light-emitting and -detecting elements are energized intermittently, if noise is generated due to an extraneous electromagnetic wave or the like, the light-detecting element may produce a signal as if it detected a user, or light may not be well detected by the light-emitting element because of fluctuations on the part of the user. Therefore, the water supply control system is prone to malfunctions.
For the removal of such noise, the detection level of the light-detecting element may be increased higher than the level of the noise. The increased detection level of the light-detecting element, however, results in a reduction in the actual sensitivity with which users can be detected.